U.S. Pat. No. 3,900,444 describes the use of alkali salts of phosphinic or diphosphinic acids to flame retard saturated polyesters. These compounds have the serious disadvantage of being water soluble thus making the resulting compositions susceptible to a loss of flame retardancy in an aqueous environment such as in laundering of fabrics prepared from these polyester compositions. U.S. Pat. No. 3,786,114 describes the use of barium or cadmium salts of either phenylphosphinic acid or a mono or diphenylphosphoric acids for use as flame retardant additives for polycarbonate resins. The phenylphosphinic acid salts have the disadvantage of being oxidatively unstable and will lose their flame retardancy over a period of time. The diphenylphosphoric acid compounds could produce an acidic condition which would irritate the skin.
U.S. Pat. No. 4,049,612 discloses that poly(metal phosphinate)s are useful as smoke retardants for polyvinyl chloride resins and suggests their use as flame retardants for polymers such as polyester and nylon.